Radar apparatuses are conventionally used for the purpose of improving driving safety of automobiles (refer to PTL 1). A radar apparatus of this type includes a transmitting unit, a receiving unit, a plurality of mixer units, a plurality of amplifier units, and a signal processing unit. The transmitting unit transmits radar waves. The receiving unit receives incoming waves through each of a plurality of reception antennas. The plurality of mixer units each mix the incoming wave received by each reception antenna with the radar wave transmitted by the transmitting unit and generate a beat signal. The plurality of amplifier units each amplify the beat signal. The signal processing unit detects the distance to a target that has reflected the radar waves and the azimuth in which the target is present (incoming azimuth) based on the results of analysis on the beat signals amplified by the amplifier units.
Usually, each amplifier unit includes a filter and an amplifier. The filter allows passage of a required frequency component of the beat signal generated by the mixer unit. The amplifier amplifies the beat signal that has passed through the filter. The filter is generally composed of a differentiating circuit that has a capacitor and a resistor.